1. FIELD OF THE INVENTION
This invention relates to a light exposure apparatus, and particularly to a light exposure apparatus suitable for use in the manufacture of LSIs having fine patterns.
2. DESCRIPTION OF THE PRIOR ART
As described in U.S. Pat. No. 4,566,795 issued to Nippon Kagaku K.K., on Jan. 28, 1986, light is directed to an alignment pattern and higher-order diffracted light generated therefrom is used to detect the alignment pattern. This is because the waveform of the alignment pattern detected by using the higher-order diffracted light is so simple that the position of the alignment pattern can be detected with high precision by a simple algorithm.
However, it is the present situation that when the alignment pattern is detected, attention is not paid particularly to the correction of the detected alignment pattern signal for the background, and hence to the correction of the distortion of the signal based on the inhomogeneous intensity distribution of the light by which the alignment pattern is irradiated.